Damn I really need to look at the std more often.

I'm passing by value here. So the data is copied into a new string and returned. This may be a best practice if you don't want to modify the original string. I would normally take a value like this by reference or use RVO but this looked like a fairly clean implementation. For its use case, passing by value is probably enough here.

Is mutating an original string a best practice?

Both string and algorithm are included in the test cases already. So we have access to them via the code that runs our code.

Can never overuse templates. 😉😂

Template overuse detected!
Also this solution is not so good because of 55

?? 😅

Read this about how to use proper markdown so spaces remain (among other things) when pasting code here.

I seem to be having issues with random tests for c++.

Expected: equal to xgay iZay !
Actual: xgay iZay!

^ As you can see the expected output has more whitespaces between the words than it should.

Edit: It seems this comment section actually clears up the extra whitespaces so the example doesn't look incorrect. But I can assure you extra whitespace is what showed up in the output.